Means and method of locating rocker arms on a rocker shaft



June 23, 1964 R. HUTCHISON 3,138,146

MEANS AND METHOD OF LOCATING ROCKER ARMS ON A ROCKER SHAFT Filed Nov.20, 1962 Fig, 4 (PRIOR ART) INVENTOR.

JAMES R. HUTCH ISON United States Patent The present invention relatesgenerally to automobile engines and more particularly to a means andmethod of locating rocker arms on a rocker shaft.

The primary object of this invention is to provide a rocker arm assemblywherein the rocker arms are located on a rocker shaft by positivelylocked retm'ning means without binding or unnecessary friction, soallowing the rocker arms to operate more efiiciently, particularly athigh speeds.

Another object of this invention is to provide a rocker arm assemblywherein the retaining means is adjustable to permit the use of shims toalign the rocker arms precisely with their respective valves.

A further object of this invention is to provide rocker arm retainingmeans which is adaptable to many different engines without requiringmodifications to the engines.

Finally, it is an object to provide a rocker arm assembly of theaforementioned character which is simple and convenient to install andwhich will give generally eflicient and durable service.

With these and other objects definitely in view, this invention consistsin the novel construction, combination and arrangement of elements andportions, as will be hereinafter fully described in the specification,particularly pointed out in the claims, and illustrated in the drawingwhich forms a material part of this disclosure, and in which:

FIGURE 1 is a side elevation view of part of a rocker arm assembly;

FIGURE 2 is an enlarged sectional view taken on 2-2 of FIGURE 1;

FIGURE 3 is a sectional view similar to FIGURE 2, with a modifiedretainer; and

FIGURE 4 is a side elevational view illustrating a prior art assembly.

Similiar characters of reference indicate similar or identical elementsand portions throughout the specification and throughout the views ofthe drawing.

Prior Art Referring first to FIGURE 4, the assembly includes a rockershaft supported in a plurality of spaced support bearings 12 which arefixed to the'engine 14, indicated fragmentarily in broken line. Theparticular location of the assembly and the configuration of the supporthearings will vary with different engines, but the general arrangementis somewhat standardized. On each side of each support bearing 12 arerocker arms 16 which swing freely on the rocker shaft 10 and are heldagainst the trunnions by compression springs 18 between pairs of therocker arms. Since rocker arms are conventionally cast and the end facesare not usually machined to any degree of smoothness, there isconsiderable friction between the rocker arms and trunnions on one side,and the springs on the other side. This condition is aggravated by thepressure of the springs necessary to hold Patented June 23, 1964 therocker arms in place. At low speeds the friction can be tolerated, butat high engine speeds, as in racing cars and other high speed vehicles,the friction causes losses in performance.

Improved Structure As illustrated in FIGURES 1 and 2, a rocker shaft 20is supported in spaced support bearings 22 and rocker arms 24 aremounted on the shaft on opposite sides of said support bearings. Therocker arms 24 each have an actuating arm 26 on one side which isengaged by the usual push rod 28, indicated in broken line in FIGURE 2,and is actuated from the camshaft, not shown. On the other side is avalve operating arm 30 which engages a spring biased valve 32, alsoindicated in broken line, the arrangement being well known.

To hold the rocker arms 24 in place retainers 34 are used, each retainercomprising a thin flat block with a bore 36 to fit closely over rockershaft 20. The retainer 34, as illustrated in FIGURE 2, has an extendedportion 38 split by a slot 40 extending substantially radially from bore36. The extended portion 38 is secured together by a lock screw 49 inthe manner of a split clamp, so that the retainer can be clampedsecurely on rocker shaft 20. The retainers 34 can be adjusted to holdrocker arms 26 in place against support bearings 22, with allowancw forsmall but very necessary working clearances for free operation. Ifnecessary shims can be used, as at 44-, to position the rocker armsprecisely with the ends of arms 3i) properly aligned with the respectivevalves 32. In the prior art assembly the use of shims increases thepressure on the rocker arm separating springs and consequently increasesworking friction.

Modified Structure In the configuration illustrated in FIGURE 3, thegeneral arrangement is as described above, but a modified form ofretainer is used. This retainer 4-6 has a bore 48 to fit rocker shaft2%) and is split transversely into an upper portion 50 and a lowerportion 52, which are held together by lock screws 54 on opposite sidesof the shaft. Retainer 46 can thus be applied to or removed from rockershaft 20 without the need for disassembling the shaft and rocker arms.In fact the retainers 46 can be applied to a prior art assembly withoutremoving the springs if necessary, the springs merely being compressedto allow insertion of the retainers, which are clamped in place to holdthe rocker arms. The springs are then held between locked retainers anddo not cause friction on the rocker arms.

With the fully adjustable, positive locking retainers precise clearancescan be set and held to allow the rocker arms to operate freely yetwithout undesirable play. At high engine speeds this can result in addedpower and wear on the parts is decreased at all speeds.

It is understood that minor variation from the form I of the inventiondisclosed herein may be made without departure from the spirit and scopeof the invention, and

that the specification and drawings are to be considered ReferencesCited in the file of this patent UNITED STATES PATENTS Belden Feb. 19,1924 Coatalen Dec. 22, 1925 Jones July 10, 1928 Vincent Dec. 4, 1928Andres Aug. 23, 1932 Avigdor July 25, 1939 Tebaldi Dec. 2, 1941 FOREIGNPATENTS Great Britain July 30, 1931 Mal

1. A ROCKER ARM ASSEMBLY, COMPRISING: A ROCKER SHAFT; A PLURALITY OFSUPPORTS SPACED ALONG SAID ROCKER SHAFT; A PAIR OF SPACED ROCKER ARMSMOUNTED ON SAID SHAFT BETWEEN ADJACENT SUPPORTS FOR ROCKING MOTION ONTHE SHAFT; AND A PAIR OF SPACED RETAINERS CLAMPED ON SAID ROCKER SHAFTBETWEEN ADJACENT ROCKER ARMS WITH EACH ONE OF SAID ROCKER ARMS RETAINEDAGAINST AXIAL SHIFTING BETWEEN ONE OF SAID RETAINERS AND ONE OF SAIDSUPPORTS.